Maintenance of the cells of the blood vessel wall in a quiescent state is a key component of normal vascular physiology. In this state, endothelial cells do not proliferate and have anti-thrombotic, vasodilator, and growth-inhibiting effects on the smooth muscle cells of the vessel wall. Transcriptional corepressors are believed to be important in maintaining vascular quiescence. The POU domain transcription factor, Oct-1, can block the expression of the endothelial-leukocyte adhesion molecule, E-selectin, and thus may play a key role. Although the overall goal is to define the molecular mechanism that controls vascular quiescence, three very specific aims have been proposed to examine the role of Oct-1 in the regulation of cytokine-induced E-selectin expression. First, we will employ a variety of biochemical techniques to determine what regulatory molecules are present on the E-selectin gene. Secondly, we will use single cell microinjection and co-transfection studies to characterize the function of these molecules in the regulation of E-selectin expression in response to TNFa. Finally, single cell microinjection studies will be performed to investigate the possible role of corepressor translocation in the regulation of E-selectin expression in response to a second inflammatory cytokine, IL-1. These studies will be carried out in human endothelial cells, which can be readily induced by cytokines to express E-selectin. These cells also provide us with a biologically relevant model system in which gene regulation can be examined in a true chromatin environment.